The major goal of Project 4 'is to test the hypothesis that a specific pancreatic cell type or lineage is sensitive to the[unreadable] transforming potential of activated Kras and serves as the cell-of-origin for PDAC in mouse models and in[unreadable] humans. This will be approached in Specific Aim 1 by examining PanlNs and other early lesions from mouse[unreadable] models generated in Project 1 using a series of lineage and developmental markers as well as gene[unreadable] expression profiling. Working with Project 2, biochemical analysis of signaling pathways will be investigated[unreadable] in these early lesions as well. Human tumor material (provided by the BioBank and the Experimental[unreadable] Pathology Cores) will be examined based on information derived from the mouse studies. Necessary[unreadable] immunological reagents not available commercially will be supplied by the PDAC Antibody Core. Unique cell[unreadable] surface markers of early lesions may be used by the Molecular Imaging Core for the purpose of early[unreadable] detection. In Specific Aim 2, we will use existing mouse strains and develop others to create an adult-onset[unreadable] model of PanIN and PDAC. This will involve both the use of viral vectors for delivery Cre recombinase to[unreadable] adult pancreas and knock-in mouse strains in which Cre activity is controlled both specially and temporally.[unreadable] The latter approach will establish what cells and lineages in the adult pancreas are sensitive to oncogenic[unreadable] transformation by Kras. Differential biological responses of various cell types will be correlated with[unreadable] biochemical and signaling differences determined with Project 2. Project 4 will also investigate whether[unreadable] PDAC harbors distinct subsets of cells that function as "cancer stem cells." This will be achieved in Specific[unreadable] Aim 3 though flow cytometric analysis of tumor-derived cells for stem/progenitor cell markers. Both mouse[unreadable] and human material will be examined (provided by Project 1 and the BioBank Core). Sorted cell populations[unreadable] will be tested for relative tumorigenic properties, and isolated cells will be used for additional molecular[unreadable] profiling studies. The characterization of a "cancer stem cell" component of PDAC has important implication[unreadable] for therapy, and the tools developed by Project 4 will be used by Project 3 to examine this population as a[unreadable] function of therapeutic intervention. This effort will be aided by PDAC Antibody Core (which will provide[unreadable] antibodies against unique PDAC cancer stem cell markers) and the Molecular Imaging Core (which will[unreadable] develop methods for their identification in vivo). Project 1 will examine the cancer stem cell population for[unreadable] recurrent genomic alterations.[unreadable] We expect that the identification and functional characterization of these cell types/cell states will provide[unreadable] essential information for improved therapy, diagnosis and early detection of PDAC.